diff --git a/apps/wpm/services.py b/apps/wpm/services.py
index dff05f1d..e53e2a5e 100644
--- a/apps/wpm/services.py
+++ b/apps/wpm/services.py
@@ -64,7 +64,7 @@ def get_pcoal_heat(year_s: int, month_s: int, day_s: int):
     """
     key = f'pcoal_heat_{year_s}_{month_s}_{day_s}'
     pcoal_heat = cache.get(key)
-    if pcoal_heat:
+    if pcoal_heat is not None and pcoal_heat > 0:
         return pcoal_heat
     else:
         try: